<html>
    <head>

    </head>
    <body>
        <script>
            function foo(e)
            {
                // KeyboardEvent对象
                //e 键盘事件对象
                console.log(e);
                console.log(e.ctrlKey);
                console.log(e.shiftKey);
                console.log(e.altKey);

                if(e.ctrlKey&&e.shiftKey&&e.altKey){
                    alert("你同时按下3个功能键");
                }
            }
            document.onkeydown=foo;
        </script>
    </body>
</html>